Sunscreen compositions comprising micronized, insoluble organic UV absorbers

ABSTRACT

The present invention provides a micronised, insoluble organic UV absorber which is especially suitable for use in pharmaceutical or cosmetic applications, with the exclusion of o-hydroxyphenyl-s-triazines having formula (I) in which R a , R b  and R c , independently, are hydrogen, halogen, C 1  -C 18  alkyl or C 1  -C 18  alkoxy, and R d  and R e , independently, are hydrogen or C 1  -C 18  alkoxy, with the provisos that one of R d  and R e  is always C 1  -C 18  alkoxy, and that, if R b , R c , R d  and R e  are each C 1  -C 18  alkoxy, then R a  is halogen, C 1  -C 18  alkyl or C 1  -C 18  alkoxy; and a sunscreen composition comprising the micronised, insoluble organic UV absorber together with a cosmetically compatible carrier. The UV absorber is of the oxalamide, triazine, vinyl-group containing amide or cinnamic acid amide classes.

The present invention relates to new physical forms of UV absorbers andto their use in sunscreen compositions which, in turn, are useful, inparticular, for the protection of human skin.

It has long been known that prolonged exposure to that UV radiationwhich reaches the surface of the earth can lead to the formation oferythemas or light dermatoses, as well as to an increased incidence ofskin cancers or accelerated skin aging.

Various sunscreen formulations have been proposed which include amaterial which is intended to counteract UV radiation, therebyinhibiting the said undesired effects on the skin.

A great number of compounds has been proposed for use as UV protectantsin sunscreen formulations, especially soluble organic UV absorbers andinsoluble micronised inorganic compounds, in particular zinc oxide andtitanium dioxide.

With respect to the use in sunscreen formulations of soluble organic UVabsorbers, they have disadvantages that their effectiveness as UVprotectants in terms of SPF (Sun Protection Factor) in a sunscreenformulation is often too low for commercial purposes; as a result oftheir solubility, they exhibit relatively high allergenic potential; andthat as a result of intrinsic photochemical lability, the duration ofthe protective effect is often too low.

The high specific weight of insoluble inorganic compounds, such as zincoxide and titanium dioxide leads to a reduced stability of formulationscontaining them. Moreover, such inorganic compounds have been claimed togenerate toxic radicals under the influence of light ("Redox Mechanismsin Heterogeneous Photocatalysis", Serpone et al, Electrochemistry inColloids and Dispersions, Editors Mackay and Texter, VCH PublishersInc., New York 1992).

It has now been found, surprisingly, that micronised, insoluble organicUV absorbers, when used in sunscreen formulations, provide excellent UVprotection and have at least as high an SPF rating as correspondingsunscreen formulations containing a known inorganic UV absorber. Unlikethe latter UV absorbers, micronised, insoluble organic UV absorbers showno tendency, under the influence of light, to generate radicals whichcould damage or sensitise human skin. Moreover due to their insolubilityin sunscreen formulations, micronised, insoluble organic UV absorbers donot penetrate the skin so that they are not able to exert any undesiredallergic or sensitising effects on the skin.

Accordingly, the present invention provides, as a first aspect, acomposition of matter, which is especially suitable for use inpharmaceutical or cosmetic applications, comprising a micronised,insoluble organic UV absorber, with the exclusion ofo-hydroxyphenyl-s-triazines having the formula: ##STR1## in which R_(a),R_(b) and R_(c), independently, are hydrogen, halogen, C₁ -C₁₈ alkyl orC₁ -C₁₈ alkoxy, and R_(d) and R_(e), independently, are hydrogen or C₁-C₁₈ alkoxy with the provisos that one of R_(d) and R_(e) is always C₁-C₁₈ alkoxy, and that, if R_(b), R_(c), R_(d) and R_(e) are each C₁ -C₁₈alkoxy, then R_(a) is halogen, C₁ -C₁₈ alkyl or C₁ -C₁₈ alkoxy.

Preferably, the insoluble organic UV absorber has a mean particle sizein the range of from 0.02 to 2, more preferably from 0.05 to 1.5,especially from 0.1 to 1.0μ.

The insoluble organic UV absorber may be converted into the desiredparticulate size state by conventional methods, e.g. by grinding theinsoluble organic UV absorber, in coarse particle form, in the presenceof suitable grinding aids and using known grinding apparatus, e.g., ajet, ball, vibration or hammer mill, preferably a high speed stirringmill or impact mill, especially a rotating ball mill, vibrating mill,tube mill or rod mill.

Preferably, the grinding is conducted in the presence of 0.1 to 30%,preferably 0.5 to 15% by weight, based on the micronised, insolubleorganic UV absorber, of a grinding aid such as an alkylatedvinylpyrrolidone polymer, a vinylpyrrolidone-vinylacetate copolymer, anacylglutamate, an acrylate-tert.-octylpropenamide copolymer, aditolylether sulphonic acid-formaldehyde condensate, a Carbomer, acommercial mixture of fatty acid esters comprising a nonionic precursersuch as tristyrylphenol ethoxylate or, in particular, a phospholipid.

Preferred insoluble UV absorbers for use in the present inventioninclude those of the oxalanilide, triazine, triazole, vinylgroup-containing amide or cinnamic acid amide classes.

One preferred class of oxalanilide UV absorbers is that having theformula: ##STR2## in which R₁ and R₂, independently are C₁ -C₁₈ alkyl orC₁ -C₁₈ alkoxy.

One preferred class of triazine UV absorbers is that having the formula:##STR3## in which R₃ and R₄, independently, are hydrogen, hydroxy or C₁-C₅ alkoxy, preferably hydrogen hydroxy or methoxy, with the exclusionof o-hydroxyphenyl-s-triazines having the formula: ##STR4## in whichR_(a), R_(b) and R_(c), independently, are hydrogen, halogen, C₁ -C₁₈alkyl or C₁ -C₁₈ alkoxy, and R_(d) and R_(e), independently, arehydrogen or C₁ -C₁₈ alkoxy, with the provisos that one of R_(d) andR_(e) is always C₁ -C₁₈ alkoxy, and that, if R_(b), R_(c), R_(d) andR_(e) are each C₁ -C₁₈ alkoxy, then R_(a) is halogen, C₁ -C₁₈ alkyl orC₁ -C₁₈ alkoxy.

A second preferred class of triazine UV absorbers is that having theformula: ##STR5## in which R₅, R₆ and R₇, independently, are H, OH, C₁-C₁₈ alkoxy, NH₂, NH--R₈ or N(R₈)₂ in which R₈ is C₁ -C₁₈ alkyl, OR₈ inwhich R₈ has its previous significance, phenyl, phenoxy or anilino inwhich the respective phenyl moieties are optionally substituted by one,two or three substitutents selected from OH, C₁ -C₁₈ alkyl or -alkoxy C₅-C₈ cycloalkyl, a methylidenecamphor group, a group --(CH═CH)_(n)C(═O)--OR₈ in which n is 0 or 1 and R₈ has its previous significance ora ##STR6## or the corresponding alkali metal, ammonium, mono-, di- ortri-C₁ -C₄ alkylammonium mono-, di- or tri-C₂ -C₄ alkanolammonium salts,or the C₁ -C₁₈ alkyl esters thereof.

One preferred class of triazole UV absorbers is that having the formula:##STR7## in which T₁ is C₁ -C₁₈ alkyl, or preferably hydrogen; and T₂ isC₁ -C₁₈ alkyl optionally substituted by a phenyl group.

A further preferred class of triazole UV absorbers is that having theformula: ##STR8## in which T₂ has its previous significance.

A preferred class of vinyl group-containing amide UV absorbers is thathaving the formula:

    R.sub.9 -(Y).sub.n --C(═O)--C(R.sub.10)═C(R.sub.11)--N(R.sub.12)(R.sub.13)(6)

in which R₉ is C₁ -C₁₈ alkyl preferably, C₁ -C₅ alkyl or phenyl in whichthe phenyl is optionally substituted by one, two or three substituentsselected from OH, C₁ -C₁₈ alkyl or -alkoxy or a group --C(═O)--OR₈ inwhich R₈ has its previous significance; R₁₀ and R₁₁ are the same ordifferent and each is C₁ -C₁₈ alkyl, preferably C₁ -C₅ alkyl orhydrogen; R₁₂ and R₁₃ are the same or different and each is C₁ -C₁₈alkyl, preferably C₁ -C₅ alkyl or hydrogen: Y is N or O; and n is 0 or1.

A preferred class of cinnamic acid amide UV absorbers is that having theformula: ##STR9## in which R₁₄ is hydroxy or O--C₁ -C₄ alkyl, preferablymethoxy or ethoxy; R₁₅ is hydrogen or C₁ -C₄ alkyl, preferably methyl orethyl; and R₁₆ is --(CONH)_(n) -phenyl in which n is 0 or 1 and thephenyl is optionally substituted by one, two or three substituentsselected from OH, C₁ -C₁₈ alkyl or -alkoxy or a group --C(═O)--OR₈ inwhich R₈ has its previous significance. Preferably R₁₆ is a phenyl,4-methoxyphenyl or phenylaminocarbonyl group.

In the compounds of formulae (1) to (7), C₁ -C₁₈ alkyl groups may bemethyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert.-butyl,n-amyl, n-hexyl, n-heptyl, n-octyl, isooctyl, n-nonyl, n-decyl,n-undecyl, n-dodecyl, tetradecyl, hexydecyl or octadecyl.

C₁ -C₁₈ alkoxy groups include methoxy, ethoxy, propoxy, butoxy,n-hexoxy, n-heptoxy, n-octoxy, isooctoxy, n-nonoxy, n-decoxy,n-undecoxy, n-dodecoxy, tetradecoxy, hexadecoxy or octadecoxy, methoxyand ethoxy being preferred.

C₅ -C₈ cycloalkyl includes cyclopentyl, cyclohexyl and cyclooctyl.

One particularly preferred compound of formula (1) isN-(2-ethoxyphenyl)-N'-(2-ethylphenyl)-ethanediamide.

Preferred compounds of formula (2) are those having the formulae:##STR10## as well as2,4,6-tris(diisobutyl-4'-aminobenzalmalonate)-s-triazine and2,4-bis(diisobutyl-4-aminobenzalmalonate)-6-(4'-aminobenzylidenecamphor)-s-triazine.

A preferred compound of formula (3) is that having the formula:##STR11##

Preferred compounds of formula (4) include those having the formulae:##STR12##

A preferred compound of formula (5) is that having the formula:##STR13##

Specific examples of preferred compounds of formula (6) include

4-octylamino-3-penten-2-one

ethyl-3-octylamino-2-butenoate

3-octylamino-1-phenyl-2-buten-1-one and

3-dodecylamino-1-phenyl-2-buten-1-one.

The compounds of formula (1) to (7) are known and may be prepared knownmethods.

The micronised, insoluble organic UV absorber may be used together withone or more UV absorbers which are conventionally used in cosmeticcompositions for the protection of human skin against UV radiation.

The phospholipid, used as the preferred grinding aid in the productionof the micronised, insoluble organic UV absorber of the presentinvention, may be of natural or synthetic origin. Naturally occuringphospholipids include phosphatidyl cholines, phosphatidyl serines,phosphatidyl inositols, phosphatidyl ethanolamines, diphosphatidylglycerols and sphingomyelins which are obtainable from such naturalsources as mammalian liver tissue, egg yolk, soybean etc. Syntheticphospholipids may be produced from natural oils such as rapeseed oil.The oil may be hydrogenated, selectively esterified and phosphorylatedto form either specific phosphatidates or mixtures of these.

As already indicated, the composition of the present invention isparticularly suitable for use in a sunscreen formulation.

Accordingly, the present invention also provides a sunscreen compositioncomprising a) 0.1 to 15%, preferably 0.5 to 10% by weight, based on thetotal composition of a micronised, insoluble organic UV absorber; and b)a cosmetically acceptable carrier.

The sunscreen composition of the present invention may be produced byphysically blending the micronised, insoluble organic UV absorber andcarrier components by any conventional method, e.g. by simply stirringthe two materials together. In a preferred procedure, a mixture of thecoarse, insoluble organic UV absorber, the grinding aid, preferably aphospholipid and the milling bodies are ground until the coarse,insoluble organic UV absorber has been converted into micronised form,as described earlier in relation to the production of the micronised,insoluble organic UV absorber. After filtering off the milling bodies,e.g. quartz sand or glass balls, the filtrate, consisting of themicronised, insoluble organic UV absorber and grinding aid components,may be blended with a cosmetically compatible carrier.

The sunscreen composition of the invention may be formulated as awater-in oil or an oil-in-water emulsion, an oil or oil-alcohol lotion avesicular dispersion of an ionic or nonionic amphiphilic lipid, a gel, asolid stick or an aerosol formulation.

When formulated as a water-in oil or an oil-in-water emulsion, thecosmetically acceptable carrier preferably comprises 5 to 50% of an oilphase, 5 to 20% of an emulsifier and 30 to 90% of water, each by weightbased on the total weight of the carrier.

The oil phase may comprise any oil conventionally used in cosmeticformulations, e.g., one or more of a hydrocarbon oil, a wax, a naturaloil, a silicone oil, a fatty acid ester or a fatty alcohol. Preferredmono- or polyols are ethanol, isopropanol, propylene glycol, hexyleneglycol, glycerine and sorbitol.

The emulsifier also may comprise any emulsifier conventionally used incosmetic formulations, e.g., one or more of an ethoxylated ester of anatural oil derivative such as a polyethoxylated ester of hydrogenatedcastor oil; a silicone oil emulsifier such as a silicone polyol; anoptionally ethoxylated fatty acid soap; an ethoxylated fatty alcohol; anoptionally ethoxylated sorbitan ester; an ethoxylated fatty acid; or anethoxylated glyceride.

The sunscreen composition of the invention may also comprise furthercomponents which are known to perform a useful function in a sunscreencomposition. Examples of such further components, include, e.g.,emollients, skin moisturisers, skin tanning accelerators, emulsionstabilisers, thickening agents such as xanthan, moisture-retentionagents such as glycerine, film formers, preservatives, perfumes andcolourants.

The sunscreen composition of the invention provides excellent protectionof the human against the damaging effects of sunlight, while permittingsafe tanning of the skin. Moreover, the sunscreen composition of theinvention has a skin waterproofing effect.

The following Examples further illustrate the present invention.

EXAMPLE 1

12.8 g of 2,4,6-trianilino-p-(carbo-2'-ethylhexyl-1'-oxy)-1,3,5-triazinehaving the formula: ##STR14## 12,8 g of a commercially-availablephospholipid (Phospholipon 90®), 135 g of water and 130 mls of glassbeads of 3 mm diameter are ground in an abrasion-resistant container, at300 rpm for 8 hours, using a suitable stirrer. The resulting suspensionis separated from the grinding beads by suction filtration. The meanparticle size diameter of ground material so obtained is 0.96μ, theparticle size range being from 0.4 to 1.7μ.

EXAMPLE 2

The suspension obtained in Example 1 is used to produce a cream havingthe following composition:

    ______________________________________    Phase A    Abil WE 09 (polysiloxane-alkylene-polyether copolymer)                                5.00%    Paraffin                    8.00%    Emulsifier (C.sub.12 /C.sub.14 -fatty acid-2-ethylhexyl                                5.00%    Microwax 7694               4.00%    Suspension from Example 1   30.00%    Propylhydroxy benzoate      0.10%    Antioxidant                 0.03%    Phase B    Glycerol                    3.00%    Methylhydroxy benzoate      0.20%    Phase C    Water                       35.82%    Sodium chloride             0.80%    Phase D    Kathon CG (stabiliser)      0.05%                               100.00%    ______________________________________

Phase A is prepared and heated to 70° C. Phase B and C, which have beenheated to 70° C., are added slowly while stirring the mixture using ahigh speed stirrer operating at 12,000 rpm. The emulsion so formed iscooled to 40° C. and, while it is stirred, using a slow speed stirreroperating at 60 rpm, phase D is added. The emulsion is cooled further to25° C. and then re-homogenised using a three roll mill.

The sunscreen factor of the homogenised emulsion is 2.4 when determinedaccording to DIN 67501.

EXAMPLE 3

12.8 g of the UV absorber having the formula: ##STR15##

12.8 g of a commercially-available phospholipid (Phospholipon 90®), 135g of water and 130 mls of grinding sand are ground in anabrasion-resistant container, at 900 rpm for 3 hours, using a suitablestirrer. The resulting suspension is separated from the grinding sand bysuction filtration. The mean particle size diameter of ground materialso obtained is 0.8μ, the particle size range being from 0.3 to 1.1μ.

The SPF values are determined for compounds (24) and (21) according toDIN 67501. Compounds (24) and (21) are firstly micronised to the sameparticle size characteristics and then incorporated, at a concentrationof 3% by weight, into a standard water-in-oil emulsion. For the purposeof comparison titanium, dioxide is evaluated under the same conditions.The results obtained are set out below:

    ______________________________________    UV Protectant   SPF Value    ______________________________________    Titanium dioxide                    2.3    Compound (24)   2.4    Compound (21)   2.5    ______________________________________

These results show that emulsions according to the present inventionhave SPF values which are at least as high as that obtained with TiO₂,without the potential toxicity hazards associated with the latter.

EXAMPLE 4

25 g of 2,2'-Methylene-bis-6-(2H-benzotriazol)-2-yl)!-4-(1,1,3,3-tetramethylbutyl)-phenol, 5 g ofLuviskol VA 64®, 75 g of water and 50 mls of zirconium beads are groundin an abrasion-resistant container, at 900 rpm for 60 hours, using asuitable stirrer. The resulting suspension is separated from thegrinding beads by suction filtration. The mean particle size diameter ofground material so obtained is 0.15μ.

We claim:
 1. A composition of matter, suitable for use in pharmaceuticalor cosmetic compositions, consisting of a micronised, insolubleoxalanilide, triazine, triazole, vinyl group-containing amide orcinnamic acid amide organic UV absorber having a mean particle size inthe range of from 0.02 to 2.0μ, with the exclusion ofo-hydroxyphenyl-s-triazines having the formula: ##STR16## in whichR_(a), R_(b) and R_(c), independently, are hydrogen, halogen, C₁ -C₁₈alkyl or C₁ -C₁₈ alkoxy, and R_(d) and R_(e), independently, arehydrogen or C₁ -C₁₈ alkoxy, with the provisos that one of R_(d) andR_(e) is always C₁ -C₁₈ alkoxy, and that, if R_(b), R_(c), R_(d) andR_(e) are each C₁ -C₁₈ alkoxy, then R_(a) is halogen, C₁ -C₁₈ alkyl orC₁ -C₁₈ alkoxy.
 2. A composition according to claim 1 in which themicronised, insoluble organic UV absorber has been produced by grindingthe insoluble organic UV absorber, in coarse particulate form, in agrinding apparatus in the presence of a grinding aid, until theinsoluble organic UV absorber has been converted into micronised form.3. A composition according to claim 2 in which the grinding apparatus isa jet, ball, vibration or hammer mill.
 4. A composition according toclaim 2 in which the grinding aid is used in an amount of 0.1 to 30% byweight of the insoluble organic UV absorber.
 5. A composition accordingto claim 2 in which the grinding aid is an alkylated vinylpyrrolidonepolymer, a vinylpyrrolidone-vinylacetate copolymer, an acylglutamate, anacrylate-tert.-octylpropenamide copolymer, a ditolylether sulphonicacid-formaldehyde condensate, a Carbomer, a commercial mixture of fattyacid esters comprising a nonionic precurser or a phospholipid.
 6. Acomposition according to claim 5 in which the grinding aid is aphospholipid.
 7. A composition according to claim 6 in which thephospholipid is one or more of a phosphatidyl choline, phosphatidylserine, phosphatidyl inositol, phosphatidyl ethanolamine, diphosphatidylglycerol or a sphingomyelin.
 8. A composition according to claim 1 inwhich the UV absorber is an oxalanilide and has the formula: ##STR17##in which R₁ and R₂, independently are C₁ -C₁₈ alkyl or C₁ -C₁₈ alkoxy.9. A composition according to claim 8 in which the UV absorber isN-(2-ethoxyphenyl)-N'-(2-ethylphenyl)-ethanediamide.
 10. A compositionaccording to claim 1 in which the UV absorber is a triazine and has theformula: ##STR18## in which R₃ and R₄, independently, are hydrogen,hydroxy or C₁ -C₅ alkoxy.
 11. A composition according to claim 10 inwhich R₃ and R₄, independently, are hydrogen, hydroxy or methoxy.
 12. Acomposition according to claim 11 in which the UV absorber has theformula: ##STR19## or is2,4,6-tris(diisobutyl-4'-aminobenzalmalonate)-s-triazine or2,4-bis(diisobutyl-4-aminobenzalmalonate)-6-(4'-aminobenzylidenecamphor)-s-triazine.13. A composition according to claim 1 in which the UV absorber is atriazine and has the formula: ##STR20## in which R₅, R₆ and R₇,independently, are H, OH, C₁ -C₁₈ alkoxy, NH₂, NH--R₈ or N(R₈)₂ in whichR₈ is C₁ -C₁₈ alkyl, OR₈ in which R₈ has its previous significance,phenyl, phenoxy, or anilino in which the respective phenyl moieties areoptionally substituted by one, two or three substitutents selected fromOH, C₁ -C₁₈ alkyl or -alkoxy, C₅ -C₈ cycloalkyl, a methylidenecamphorgroup, a group --(CH═CH)_(n) C(═O)--OR₈ in which n is 0 or 1 and R₈ hasits previous significance or a ##STR21## or the corresponding alkalimetal, ammonium, mono-, di- or tri-C₁ -C₄ alkylammonium, mono-, di- ortri-C₂ -C₄ alkanolammonium salts, or the C₁ -C₁₈ alkyl esters thereof.14. A composition according to claim 13 in which the UV absorber is atriazine having the formula: ##STR22##
 15. A composition according toclaim 1 in which the UV absorber is a triazole and has the formula:##STR23## in which T₁ is C₁ -C₁₈ alkyl or hydrogen; and T₂ is C₁ -C₁₈alkyl optionally substituted by a phenyl group.
 16. A compositionaccording to claim 15 in which T₁ is hydrogen.
 17. A compositionaccording to claim 16 in which the triazole has the formula: ##STR24##18. A composition according to claim 1 in which the UV absorber is atriazole and has the formula: ##STR25## in which T₂ is C₁ -C₁₈ alkyloptionally substituted by a phenyl group.
 19. A composition according toclaim 18 in which the UV absorber is 2,2'-methylene-bis-6-(2H-benzotriazol-2-yl)!4(1,1,3,3-tetramethylbutyl)-phenyl.
 20. Acomposition according to claim 1 in which the UV absorber is a vinylgroup-containing amide UV absorber having the formula:

    R.sub.9 -(Y).sub.n --C(═O)--C(R.sub.10)═C(R.sub.11)--N(R.sub.12)(R.sub.13)(6)

in which R₉ is C₁ -C₁₈ alkyl or phenyl in which the phenyl is optionallysubstituted by one, two or three substituents selected from OH, C₁ -C₁₈alkyl or -alkoxy or a group --C(═O)--OR₈ in which R₈ has its previoussignificance; R₁₀ and R₁₁ are the same or different and each is C₁ -C₁₈alkyl or hydrogen; R₁₂ and R₁₃ are the same or different and each is C₁-C₁₈ alkyl or hydrogen: Y is N or O; and n is 0 or
 1. 21. A compositionaccording to claim 20 in which R₉ is C₁ -C₅ alkyl or phenyl in which thephenyl is optionally substituted by one, two or three substituentsselected from OH, C₁ -C₁₈ alkyl or -alkoxy or a group --C(═O)--OR₈ inwhich R₈ is as defined in claim 18; R₁₀ and R₁₁ are the same ordifferent and each is C₁ -C₅ alkyl or hydrogen; R₁₂ and R₁₃ are the sameor different and each is C₁ -C₅ alkyl or hydrogen: Y is N or O; and n is0 or
 1. 22. A composition according to claim 21 in which the UV absorberis:4-octylamino-3-penten-2-one ethyl-3-octylaniino-2-butenoate3-octylamino-1-phenyl-2-buten-1-one and3-dodecylamino-1-phenyl-2-buten-1-one.
 23. A composition according toclaim 1 in which the UV absorber is a cinnamic acid amide having theformula: ##STR26## in which R₁₄ is hydroxy or O--C₁ -C₄ alkyl; R₁₅ ishydrogen or C₁ -C₄ alkyl; and R₁₆ is -(CONH)_(n) -phenyl in which n is 0or 1 and the phenyl is optionally substituted by one, two or threesubstituents selected from OH, C₁ -C₁₈ alkyl or -alkoxy or a group--C(═O)--OR₈ in which R₈ is as defined in claim
 18. 24. A compositionaccording to claim 23 in which R₁₄ is hydroxy, methoxy or ethoxy; R₁₅ ishydrogen, methyl or ethyl; and R₁₆ is a phenyl, 4-methoxyphenyl orphenylaminocarbonyl group.
 25. A sunscreen composition comprising a) 0.1to 15% by weight of a micronised, insoluble oxalanilide, triazine,triazole, vinyl group-containing amide or cinnamic acid amide organic UVabsorber having a mean particle size in the range of from 0.02 to 2.0μ;and b) a cosmetically acceptable carrier.
 26. A sunscreen compositionaccording to claim 25 comprising a) 0.5 to 10% by weight of amicronised, insoluble organic UV absorber, and b) a cosmeticallyacceptable carrier.
 27. A composition according to claim 25 in which themicronised, insoluble organic UV absorber has been produced by grindingthe insoluble organic UV absorber, in coarse particulate form, in agrinding apparatus in the presence of a grinding aid, until theinsoluble organic UV absorber has been converted into micronised form.28. A composition according to claim 27 in which the grinding apparatusis a jet, ball, vibration or hammer mill.
 29. A composition according toclaim 27 in which the grinding aid is used in an amount of 0.1 to 30% byweight of the insoluble organic UV absorber.
 30. A composition accordingto claim 27 in which the grinding aid is an alkylated vinylpyrrolidonepolymer, a vinylpyrrolidone-vinylacetate copolymer, an acylglutamate, anacrylate-tert.-octylpropenamide copolymer, a ditolylether sulphonicacid-formaldehyde condensate, a Carbomer, a commercial mixture of fattyacid esters comprising a nonionic precurser, or a phospholipid.
 31. Acomposition according to claim 30 in which the grinding aid is aphospholipid.
 32. A composition according to claim 31 in which thephospholipid is one or more of a phosphatidyl choline, phosphatidylserine, phosphatidyl inositol, phosphatidyl ethanolamine, diphophatidylglycerol or a splhingomyelin.
 33. A composition according to claim 25 inwhich the micronised, insoluble organic UV absorber is used togetherwith one or more UV absorbers which are conventionally used in cosmeticcompositions for the protection of human skin against UV radiation. 34.A sunscreen composition according to claim 25 which is formulated as awater-in oil or an oil-in-water emulsion, an oil or oil-alcohol lotion,a vesicular dispersion of an ionic or nonionic amphiphilic lipid, anoil-alcohol or alcohol gel, a solid stick or an aerosol formulation. 35.A sunscreen composition according to claim 34 which is formulated as awater-in oil or an oil-in-water emulsion and component b) comprises 5 to50% of an oil phase, 5 to 20% of an emulsifier and 30 to 90% of water,each by weight based on the total weight of the carrier.
 36. A sunscreencomposition according to claim 35 in which the oil phase comprises oneor more of a hydrocarbon oil, a wax, a natural oil, a silicone oil, afatty acid ester or a fatty alcohol.
 37. A sunscreen compositionaccording to claim 35 in which the emulsifier comprises one or more ofan ethoxylated ester of a natural oil derivative; a silicone oilemulsifier; an optionally ethoxylated fatty acid soap; an ethoxylatedfatty alcohol; an optionally ethoxylated sorbitan ester; an ethoxylatedfatty acid; or an ethoxylated glyceride.
 38. A sunscreen compositionaccording to claim 37 in which the ethoxylated ester of a natural oilderivative is a polyethoxylated ester of hydrogenated castor oil; andthe silicone oil emulsifier is silicone polyol.
 39. A sunscreencomposition according to claim 25 in which the sunscreen compositionalso comprises one or more further components selected from emollients,skin moisturisers, skin tanning accelerators, emulsion stabilisers,thickening agents, moisture retention agents, film formers,preservatives, perfumes and colourants.
 40. A composition according toclaim 1 which the micronised, insoluble organic UV absorber has a meanparticle size in the range of from 0.05 to 1.5μ.
 41. A compositionaccording to claim 40 in which the micronised, insoluble organic UVabsorber has a mean particle size in the range of from 0.1 to 1μ.
 42. Acomposition according to claim 25 in which the micronised, insolubleorganic UV absorber has a mean particle size in the range of from 0.05to 1.5μ.